How many protons , electrons, and neutrons are in an atom?

How many protons, electrons, and neutrons are in an atom? http://physicsed.buffalostate.edu/Wiley/CJ6e/img30/PTE.gif

Step 1 • Use your periodic table to find an element http://education.jlab.org/qa/pen_number.html

Step 2 • The number of Protons (+ charge) • The atomic number = # protons • Kr has 36 protons http://education.jlab.org/qa/pen_number.html

Step 3 • The number of Electrons (- charge) • Remember atoms have no overall charge. • Atoms must have an equal # of protons and electrons • #protons=#electrons • Kr has 36 electrons

Step 4 • The number of Neutrons (no charge) • Mass # (atomic weight rounded to nearest whole #) • Neutrons = Mass # -Protons • Neutrons= 84 –36 • Neutrons = 48

Summary • Number of Protons = Atomic # • Number of Electrons = Protons • Number of Neutrons = Mass # - Protons

Problems • Find the protons (p+), electrons (e-), neutrons (n) of Oxygen • Find the p+, e-, n of Xenon (Xe) • Find the p+, e-, n of Zirconium (Zr)

Oxygen (O)p+, e-, n • Number of Protons = Atomic # • Number of Electrons = Protons • Number of Neutrons = Mass # - Protons • Protons = 8 • Electrons = 8 • Neutrons = 16-8 = 8

Xenon (Xe)p+, e-, n • Number of Protons = Atomic # • Number of Electrons = Protons • Number of Neutrons = Mass # - Protons • Protons = 54 • Electrons = 54 • Neutrons = 131-54 = 77

Zirconium (Zr)p+, e-, n • Number of Protons = Atomic # • Number of Electrons = Protons • Number of Neutrons = Mass # - Protons • Protons = 40 • Electrons = 40 • Neutrons = 91-40 = 51

How many protons , electrons, and neutrons are in an atom?